چكيده به لاتين
Abstract:
Titanium and its alloys have an extensive application in manufacturing orthopedic and medical implants. This is because of having a combination of high strength to weight ratio, low elastic modulus, very high resistance to corrosion and good biocompatibility. Although having good biocompatibility, commercial pure titanium has low strength. So the trend of studying different titanium alloys has been emerged.
In the present research, heat treating of a biomedical beta titanium alloy, TMZF (Ti-12Mo-6Zr-2Fe), has been done. The purpose of this research is to achieve an appropriate combination of strength, flexibility, elastic modulus and hardness for the alloy, to develop a homogeneous matrix structure (recrystallized fine beta grains), to precipitate fine alpha phase homogeneously and to prevent from the formation of omega phase as much as possible. After melting and alloying and ingot production, the ingot was hot rolled in two steps. Then, several samples were cut for the following tests. The samples were annealed in different temperatures to obtain the best temperature. Next, after annealing, some samples were cold rolled to two reduction percents of 18% and 26% and finally, all the prepared samples were aged in different temperatures and times.
770°C was chosen as the best temperature for annealing. In the samples aged below 500°C, omega precipitation formed and in the samples aged above this temperature, α precipitation formed. Also, it was concluded that in the aging time of 6 hours, 350°C and 450°C cause the most hardening in the alloy as much as 509HV and 506.66HV resppectively. However, the omega phase reduces the ductility. Cold rolling before aging did not have much effect on the properties of the alloy. Generally, among the conditions tested in this research, aging in 500°C for 6 hours can be known the most appropriate for aging of this alloy.
Keywords: beta titanium alloy, heat treatment, aging, cold work
